Charles Grassley of Iowa has become the 10th longest-serving Senator in U.S. history with 39.3 years of service.
Grassley, who currently serves as President pro tempore of the U.S. Senate, was first elected to the Senate in 1980.
He is only the second Iowan to hold that post, a position that has historically been held by the most senior member of the majority party in the Senate.
That puts Grassley third in the line of presidential succession after the vice president and the Speaker of the House.
The New Hartford, Iowa Republican is also chairman of the Senate Finance Committee.
He formerly chaired the Senate Judiciary Committee and continues to serve as a senior member there.
Grassley is currently one of only two farmers serving in the Senate and has not missed a vote since 1993.